Literaturdatenbank
Literaturdatenbank |
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Kazmaier, R. T., Hellgren, E. C., Synatzske, D. R., & Rutledge, J. C. (2001). Mark-recapture analysis of population parameters in a texas tortoise (gopherus berlandieri) population in southern texas. Journal of Herpetology, 35(3), 410–417.
Added by: Admin (14 Aug 2008 22:46:47 UTC) Last edited by: Beate Pfau (14 Mar 2009 12:43:35 UTC) |
| Resource type: Journal Article BibTeX citation key: Kazmaier2001e View all bibliographic details  |
Categories: General Keywords: Gopherus, Gopherus berlandieri, Habitat = habitat, Nordamerika = North America, Schildkröten = turtles + tortoises, Testudinidae Creators: Hellgren, Kazmaier, Rutledge, Synatzske Collection: Journal of Herpetology |
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| Abstract |
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Gopherus berlandieri Testudinidae Techniques to assess population changes in reptiles across large landscapes are a conservation and management need. We studied a population of Texas tortoises (Gopherus berlandieri) on a large study area (6150 ha) of contiguous thornscrub vegetation in southern Texas from 1990 to 1999. We examined cohort and temporal variation in capture probabilities; and estimated survival, population size, and λ (finite population growth rate) for a population of Texas tortoises. We captured 2128 tortoises a total of 3132 times during the study period. The distribution of the frequency of captures by sex varied during the active season and across years, but annual capture probabilities were similar between sexes. The ratio of juvenile to adults varied by a month-by-year interaction. Tortoises exhibited a temporary response to marking that was modeled in survival analysis. Capture probabilities of adult tortoises on an annual basis ranged from 0.12-0.38, and annual survival rate of adults was estimated to be 0.79 ± 0.05. We estimated the density of the adult population to be 0.26 tortoises/ha, a level of magnitude lower than previous work conducted on habitat islands. Lambda (population growth rate) was estimated to be 0.981 (95% confidence limits: 0.945-1.019) from a Jolly-Seber model. Road-cruising was an effective large-scale method for population monitoring of the Texas tortoise in our study area and may prove useful in thornscrub habitats that compose the majority of its geographic range. Added by: Admin Last edited by: Beate Pfau |